In an information processing apparatus, such as a server, multiple processors, e.g., central processing units (CPUs), may be provided as arithmetic processing apparatuses and may be connected to each other. In such an information processing apparatus, CPUs may communicate to each other for embodying parallel computing (parallel processing), for example.
As exemplified in FIG. 19, in an information processing apparatus 100, data, e.g., packets, sent from another CPU 200 or another apparatus that is not illustrated (hereinafter, referred to as the “sender” or “source”) are received and confirmed by a receiving unit 210 at an interface of a destination CPU 200. The received and confirmed packets are then arbitrated by a router unit 220, pass through a cache unit 230, and are notified to a core unit 240 as a processor core, which serves as an arithmetic processing unit. While only one core unit 240 is depicted in the CPU 200 in FIG. 19, each CPU 200 may include multiple core units 240.
In the meantime, a related technique is known in which a communication control apparatus selects an output packet based on priority information provided in packets, and updates the priority information of packets that are not selected, based on weight information (refer to Patent Document 1, for example).
Another related technique is also known in which each of multiple CPUs attaches latency information corresponding to a destination hardware resource in a routing table of that CPU, to a transmission packet (refer to Patent Document 2, for example). In this technique, upon receiving multiple packets, each of multiple crossbars carries out a priority arbitration process for preferentially sending a packet having a greater latency to the destination hardware resource.
Patent Document 1: Japanese Laid-Open Patent Publication No. 2013-135387
Patent Document 2: Japanese Laid-Open Patent Publication No. 2009-194510
Preferably, an arbitration in the router unit 220 is carried out in an equalized manner for all interfaces (e.g., sources). For example, when the router unit 220 arbitrates among (selects one from) packets from sources using the genuine least recently used (LRU) scheme or the like, arbitration participation signals from the sources concentrate on a single point with an increase in the number of sources, which results in an increase in the size of the circuit for carrying out the LRU arbitration (selection).